Javascript 如何在不同的对象字段中查找重复值？

如何使用

mongoose

搜索不同字段中的重复值

这里是示例文档：

{
 "followers": {
               {
                "_id": "5bf6d610d3a3f31a6c75a9f4"
               },
               {
                "_id": "5bf6d610d3a3f31a6c75a8c3"
               }
              },
 "following": {
               {
                "_id": "5bf6d610d3a3f31a6c75a9f4"
               },
               {
                "_id": "5bf6d610d3a3f31a6c75b7a2"
               }
              },
}

{
 {
  "_id": "5bf6d610d3a3f31a6c75a9f4"
 }
}

db.collection.aggregate([
    { $unwind : "$followers"},
    { $unwind : "$following"},
    { $project : {
        _id: 0,
        matchId: { $cond: [ {$eq: [ "$followers._id", "$following._id" ]} ,
          "$following._id", null ] }
    }},
    {$match : {"matchId" : {$ne : null}}}
])

/* 1 */
{
    "matchId" : "5bf6d610d3a3f31a6c75a9f4"
}

---

我想在

followers

和

followers

字段下找到相同的

\u id

值

预期输出：

{
 "followers": {
               {
                "_id": "5bf6d610d3a3f31a6c75a9f4"
               },
               {
                "_id": "5bf6d610d3a3f31a6c75a8c3"
               }
              },
 "following": {
               {
                "_id": "5bf6d610d3a3f31a6c75a9f4"
               },
               {
                "_id": "5bf6d610d3a3f31a6c75b7a2"
               }
              },
}

{
 {
  "_id": "5bf6d610d3a3f31a6c75a9f4"
 }
}

db.collection.aggregate([
    { $unwind : "$followers"},
    { $unwind : "$following"},
    { $project : {
        _id: 0,
        matchId: { $cond: [ {$eq: [ "$followers._id", "$following._id" ]} ,
          "$following._id", null ] }
    }},
    {$match : {"matchId" : {$ne : null}}}
])

/* 1 */
{
    "matchId" : "5bf6d610d3a3f31a6c75a9f4"
}

---

我应该使用什么查询？

试试这个：

{
 "followers": {
               {
                "_id": "5bf6d610d3a3f31a6c75a9f4"
               },
               {
                "_id": "5bf6d610d3a3f31a6c75a8c3"
               }
              },
 "following": {
               {
                "_id": "5bf6d610d3a3f31a6c75a9f4"
               },
               {
                "_id": "5bf6d610d3a3f31a6c75b7a2"
               }
              },
}

{
 {
  "_id": "5bf6d610d3a3f31a6c75a9f4"
 }
}

db.collection.aggregate([
    { $unwind : "$followers"},
    { $unwind : "$following"},
    { $project : {
        _id: 0,
        matchId: { $cond: [ {$eq: [ "$followers._id", "$following._id" ]} ,
          "$following._id", null ] }
    }},
    {$match : {"matchId" : {$ne : null}}}
])

/* 1 */
{
    "matchId" : "5bf6d610d3a3f31a6c75a9f4"
}

输出：

{
 "followers": {
               {
                "_id": "5bf6d610d3a3f31a6c75a9f4"
               },
               {
                "_id": "5bf6d610d3a3f31a6c75a8c3"
               }
              },
 "following": {
               {
                "_id": "5bf6d610d3a3f31a6c75a9f4"
               },
               {
                "_id": "5bf6d610d3a3f31a6c75b7a2"
               }
              },
}

{
 {
  "_id": "5bf6d610d3a3f31a6c75a9f4"
 }
}

db.collection.aggregate([
    { $unwind : "$followers"},
    { $unwind : "$following"},
    { $project : {
        _id: 0,
        matchId: { $cond: [ {$eq: [ "$followers._id", "$following._id" ]} ,
          "$following._id", null ] }
    }},
    {$match : {"matchId" : {$ne : null}}}
])

/* 1 */
{
    "matchId" : "5bf6d610d3a3f31a6c75a9f4"
}

---

followers

和

follower

将是数组。是吗？@HardikShah是的！谢谢，但是我如何在单个文档中进行查询（我想在单个文档中但在两个不同的字段中查找重复ID）是的，您可以使用我提供的相同代码片段进行查询。只需将

$match

添加到聚合顶层的特定Id即可。你能发布你的整个样本数据结构吗？所以，我可以修改您的要求。